The growth and development of rice (Oryzae sativa)
seedlings was shown to be regulated epigenetically by a fungal
endophyte. In contrast to un-inoculated (nonsymbiotic) plants,
endophyte colonized (symbiotic) plants preferentially allocated
resources into root growth until root hairs were well established.
During that time symbiotic roots expanded at five times the rate
observed in nonsymbiotic plants. Endophytes also influenced sexual
reproduction of mature big sagebrush (Artemisia tridentata)
plants. Two spatially distinct big sagebrush subspecies and their
hybrids were symbiotic with unique fungal endophytes, despite
being separated by only 380 m distance and 60 m elevation. A
double reciprocal transplant experiment of parental and hybrid
plants, and soils across the hybrid zone showed that fungal endophytes
interact with the soils and different plant genotypes to confer
enhanced plant reproduction in soil native to the endophyte and
reduced reproduction in soil alien to the endophyte. Moreover,
the most prevalent endophyte of the hybrid zone reduced the fitness
of both parental subspecies. Because these endophytes are passed
to the next generation of plants on seed coats, this interaction
provides a selective advantage, habitat specificity, and the
means of restricting gene flow, thereby making the hybrid zone
stable, narrow and potentially leading to speciation.